Efecto de acuicultura simbiótica en la prevalencia bacteriana en precrías de camarón (litopenaeus vannamei).

Abstract

The intensification of aquaculture has increased the deterioration and subsequent eutrophication of water used in farming. In response to this, there is a need to implement technologies with ecosystem-based approaches. Symbiotic aquaculture is a technique that promotes sustainability by interacting with the environment, improving water quality and organisms, increasing growth rates, and inhibiting pathogenic bacteria. The objective of this study was to determine the effect of symbiotic aquaculture on bacterial prevalence in shrimp postlarvae (Litopenaeus vannamei). The experiment was conducted at the Mariculture Station in the Faculty of Agricultural Sciences, part of the Technical University of Machala. A completely randomized design (CRD) was used, with one experimental factor (Symbiotic Aquaculture) and three treatments: Control, AS without prior maturation, and AS +15 days of maturation, each with three replicates, forming nine experimental units (plastic tanks) distributed randomly. The analysis of bacterial prevalence of Bacillus and Vibrio in water (CFU/ml) and organisms (CFU/g) was performed using the serial dilution method and plating on selective agar plates (Chromagar Vibrio and Bacillus). Weight (mg) and length (cm) variables were measured using the LarvIA mobile application, while survival (%) was determined by manually counting postlarvae at the end of the experiment. Treatment comparisons based on bacterial prevalence in water and organisms (Bacillus and Vibrio), weight, size, and survival were conducted using one-way analysis of variance (ANOVA), following verification of the assumptions of data normality (checked with the Kolmogorov-Smirnov test) and homogeneity of variances (verified with Levene's test). In case of statistical differences between the study treatments, the Duncan's multiple range test was applied to determine where the differences or similarities lie. If some of the parametric model assumptions were not met, the Kruskal-Wallis ANOVA was used. The results showed statistically significant differences between treatments. AS without prior maturation and AS +15 days of maturation demonstrated a significant reduction in pathogenic bacterial load (Vibrio) in both water column (0.0E+00) and shrimp postlarvae (1.7E+01 and 8.3E+01, respectively). The beneficial bacterial load (Bacillus) consistently increased in AS without prior maturation and AS +15 days of maturation (3.0E+10 and 3.0E+11) in the culture medium. In contrast, the final concentrations in Control postlarvae (6.05E+04) decreased compared to AS without prior maturation and AS +15 days of maturation (3.0E+05 and 2.93E+05), which remained similar to the initial bacterial concentrations. Growth variables (weight and length) exhibited significant differences, with SA +15 days of maturation (39.97; 1.85) showing the best results compared to AS without prior maturation (31.14; 1.73), while the Control (27.22; 1.61) obtained the AS lowest growth rates. The highest survival rates were observed in AS without prior maturation (91.67) and AS +15 days of maturation (93.91), while the Control (55.43) had the lowest value. In conclusion, this study demonstrates that symbiotic aquaculture promotes the growth of beneficial bacteria (Bacillus) while suppressing pathogenic bacteria (Vibrio) in both water and organisms. It also enhances growth and survival rates, creating a healthy and nutritionally balanced environment.